Carburetor



Nov. 13, 1951 F. B. SWEENEY CARBURETOR 2 SHEETSSHEET 1 Filed Nov. 25, 1945 w y 5:? mwmg gm 7 m? Ill? N six M 1 H MQ HEV Ill l I l I E A NW n E e l IIIIED. 51

INVENTOR. FRANK B. SWEENEY NOV. 13, 1951 SWEENEY 2,574,670

CARBURETOR 3 Filed Nov. 25, 1945 2 SHEETS-SHEET 2 \l m 9 v V g m v v Q) 0S "3 0 m z Qm mm m, r\ 5% v Mag lvv m I .2- w i l 2 4- i A k l E g p k Q N a; a; Q \Q on s: mm

m a E 2 an i IN V EN T 0R.

FRANK a. SWEENEY ATTOHNEY Patented Nov. 13, 1951 CARBURETOR Frank B; Sweeney; Rochester; N assignor; to.- Ritter Company I'nc., Rochester; :Y aicor poratiomofi Delaware ApplicationN6vemlier23, 1945;"Serial N 639,257

thatthe motor will idleeither:whenthe engine: is .v cold or when it is at r-unning temperaturewithout stalling and without the -use of excessive fuel;

Qther objeets-and advantages of my invention-. sl will-be set forth more particularly in the-claims and will be apparent from thefollowing description; when-takeniin connectionwith the accom panying drawings; 'in wliieh:

Figure -1 is a view-partlyin section and*par- Another object of my' invention is to provide: 103 tially diagrammatic illustrating the pressure in a pressureinjection'carburetor-"iniwhich the fuel, and airare accurately metered undersubstantially all conditions offoperationto the end that the-proper'ratio of fuel to air-*issuppiied'to"the engine for optimum: results throughout the range'of operation'of the engine.

Anothenobject ofmyinvention is to provide: a pressure injection carburetor wherein means: are provided for automatically supplying" a rich I mixture of atomized fuel when the engine is: 291

started. 7

Another object'of my invention is to provide: a pressure injection carburetor in which, under normal conditions of operatiomjthe fuel pres sure at the fuel metering valve is maintained substantially" constant;

Another object. of 'myjinvention" is to provide; a'pressure' injection type of carbur'etorin which" anair metering means or disc governs'the opera tion of the fuelmetering valvesotha't'the; ratio of ,fuel to air is varied'in the proper proportions for best operation under normal cruising condi'- tions and,'atfthe same timei,jprovision.isi made for increasing the ratio of "fuelto air automati cally when the engine isflatiorjnear fulllload for any. given engine speed or is being suddenly and rapidly accelerated.

A further object of "my invention is toprovide' a pressure injection carburetor in' which, the

jectio-rr carburetor of 1 my invention;

Figure 2- is a side elevation of the pressure inj action-carburetor of my invention wlooking fromthe left of Figure 1 substantially" Figure- 3 is an enlarged sectional view" of a portion --of* Figure-J 1 showing the fuel "pressure regulatingg valve together with its associated parts; and

Figure 4* is an enlarged sectional view of aportion' of Figure 1- showing the air andfuel metering valves and "their associated parts.

The carburetor of -my invention comprises amain body section -l=land a mixing chamber section I2 which" are* provided with flangesse 5 cured. together; as show-nat I 3; Theoarburetor" is? connected to the intake-manifold; partially=- indicated--at M, of the engine with which" the carburetor is associated. Above the mixingchamber'section'H 'is-an-air intake section IS. The" particular carburetor illustrated is of the downi-draft type which is the preferred form; However; thi'stis primarilyfor-purposesof illu'stration" as the-principles of m-y' invention -may'- bedncorporatedirrother types of carburetors;

The .carburetor is" provided. with the usual" throttle valve *lfii mounted on'ashaft H; carried'; in bores formed in bosses: Thefunctionand operation of a throttle va-1ve-arewellknown in. the art towhich 'this' invention" apfuel is introducedinto the airstream under pres- 4o plies andtno descriptiom of its function and sure .anclby' means of nozzles so'constructed" and arrangedasto secure betteratomizationofthe fuel and substantially uniform" co-mingling of? the fuel vaporand airq'and distribution of mar and air to-the engine cylinders.

Still another" object of myinvention is to provide an improveditemperatureicontrol fortheair entering the carburetor particularly adapted for 'use in' connection with a pressure injection carburetor, and" in" which all: the-air passing tothe carburetor has a definite: and measurable" affect on the'fuel meteringvalve and the supply of? fuel to the carburetor;

My invention further contemplates the pro--- operation"isfbelivedto benecessary; The main-- body section and; the-"mixing chamber section are" provided-"with passa'ges"*which are connected to form an' air' flow passage I 8 throughwhich-airflows'to thedntake-maniffld of the engine" under the partial vacuum or sub atmospheric pressureconditions created b'y 'the reciprocation of thepi'stons thereof? Theair?- flow passage"- H; isnorma11yalmost: closecF-by an air metering discl 9 which is mov able from'theclosedposition shown to a-par tia'll'y" or fully open position;- in- -accordance-with" the, differential in pressure existent onoppositesidescf the air--metering disc. The-:air'metervision of improved meansforidling themotor-so" ing discassumes a po'sitiom dictated by the pressure conditions existent and thus its position reflects or measures the volume of air passing through the air flow passage. While I have shown a disc air metering device and believe that this has distinct advantages, other air metering devices might be employed in combination with other parts of the carburetor of my invention. l

The air metering disc 19 is connected, ina manner presently described, to a fuel metering valve generally indicated by the numeral 2|. The fuel metering valve is located in the fuel line, generally designated by the numeral 22, the fuel line being connected to a fuel pump. diagrammatically illustrated by the numeral 23.

The fuel pump 23 is driven in the usual manner from the engine cam shaft and is of a type in common use adapted to deliver gasoline to the fuel line at a substantially constant pressure regardless of engine operating speed. The fuel pump 23 is connected to the fuel line by a pipe 24 (Figure 3) which extends into a threaded opening formed in the main body section of the carburetor. A bore 26, communicating with the pipe 24, opens into a chamber 21 in which is housed a strainer 28. Access to the chamber 21 and the strainer 28 for the purpose of cleaning the same, is gained through an opening in the main body section which is closed by a threaded cap 29.

The chamber 27 is in communication with an enlarged opening in the main body section which is adapted to receive a regulating valve assembly, generally indicated by the numeral 3|. The regulating valve assembly 3| comprises a valve body section 32 and a cap section 33. The valve body section 32 is supported by an annular wall provided in the casting which forms the main body section II of the carburetor. Interposed between the facing surfaces of the valve body section 32 and the annular wall formed in the casting is a gasket 34 to prevent leakage of fuel as will later appear. The cap section 33 of the regulating valve assembly is threaded into the casting as shown at 36. By threading the cap section inward, pressure is applied on the gasket 34 so as to form a seal between the surfaces.

The lower end of the valve body section 32, is provided with a valve seat 31 formed at the end of a bore 38. The bore 38 constitutes a part of the fuel line 22. Extending from the bore 38 are one or more radial passages 39 which open into an annular recess 4|. The annular recess communicates with a transversely extending passage 42, one end of which is closed by a plug 40 and which also constitutes part of the fuel line 22. The transverse passage 42 connects with a vertically extending passage 43 formed in an upwardly extending part-44 (Figure 4), which the valve stem 4! are a pair of backing plates 49 and The backing plates serve to confine a resilient diaphragm 52 between them.

The margins of the diaphragm 52 are carried on an annular ledge formed in an enlarged re- 4 cess 53 provided in the valve body section 32. An annular snap ring 54 confines the margins of the diaphragm and annular packing rings 56 are interposed between the parts on opposite sides of the diaphragm. From the above, it will be apparent that the margins of the diaphragm are rigidly held but the diaphragm is free to be flexed so as to move the valve element 46, from the position shown, to a closed position or any intermediate position in accordance with the degree of flexure of the diaphragm.

Formed in the cap section 33, is an enlarged cylindrical bore 51. A piston or pressure responsive element 58 is operable in the cylindrical bore 51 in accordance with variations in pressure existent on the opposite sides of the piston during the operation of the engine. The upper end of the cap section 33 has a threaded bore 59 adapted to receive an adjustment screw 6!. A spring 62 is interposed between the thumb piece or head 63 of the screw and a shoulder 84. The spring serves to maintain the adjusting screw from being shaken loose from its desired position of adjustment. I

A stop 55, projecting into the cylinder, is formed on the lower end of the adjusting screw which limits the upward movement of the piston 58. Annular recesses 61 are provided on opposite sides of the piston 58 for the seating of springs 68 and 69. For the purposes of this description, and as will presently appear, the lower spring 68 may be considered a pressure regulating spring, While the upper spring 69, which is the stronger of the two springs, may be termed a full load enrichment spring.

As shown more clearly in Figure 1, a bore H is provided in the main body section casting H, which extends from the air flow passage on the lower side of the throttle valve l8, upwardly to an annular recess 12 (Figure 3) formed in the pressure regulating valve assembly. The annular recess 12 communicates through a bore I3 to the space in the cylinder 51 above the piston or pressure responsive element 58.

The space above the piston 58 is thus subjected to the vacuum or sub-atmospheric pressure conditions existent in the intake manifold. The vacuum conditions in the intake manifold, as is well known in the art to which this invention applies, is determined by the operating conditions under which the engine is functioning. It is suflicient for the purpose of this invention, to state that the degree of a vacuum existent in the intake manifold, and hence in the cylinder 51 above the piston 58, is decreased upon an increase in the load conditions imposed upon the engine or when the engine is being accelerated by opening the throttle more widely.

As illustrated in Figure 3, which is also true of all the views, the parts are shown in the position which they occupy when the engine is not operating. When the engine is started, a partial vacuum is produced in the intake manifold. This sub-atmospheric pressure after the engine is running is effective in the cylinder 51 'above the piston, to draw the piston upward cient to force the piston out of engagement with 52. the endof" the stop 66 when the sub-atmospheric pressure existent in the cylinder 51 corresponds or'increases to approximatelyfull load on the engine. Byadjusting the thumb piecesubstantially the entire curve-formed by plotting the fuel-air ratio against the airflow may be changed. That is, threading the thumb pieceinwardly increases the pressure on the spring 68 which moves the valve element 46 to a more open position. The effect of this adjustment is felt overtheentire range of operation of theengine, increasing the fuel flow for any-given air flow.

The space 14 between the diaphragm and thelower side of thepiston is-vented through a passage 16 and hence, atmospheric pressureconditions are at all times existent inthe space M above the diaphragm. From the above, it will be apparent that the position of the valve 46-; with respect to its seat, is influenced-under normal conditions of operation by the factors; the fuel pressure beneath the-diaphragm; and the pressure regulating spring 69. Moreover, under certain operating conditions, as will presentlyappear, the position of the diaphragm and hence the valve 46, is affected by the spring 69 andthevacuum conditions existent in the intake manifold.

As shown most clearly in Figure 4, the fuel metering valve 2| includes afrusto-conical valve element 71, normally adapted to engage a seat 18-,formed on the end of a valve housing member-I9. The valve housing-member is threaded into telescopic relation with the upwardly extending part 44 of the main casting of the carburetor, as shown at BI. The valve element 11 is.integral with a valve stem 82 which is reciprocable in a bore 83 formed in the valve housing member 19. The upper end of the valve butts against the lower end of a stem 85 connected to. the air metering disc I9.

Adjacent its upper end the stem 85isprovided with a shoulder 84 upon which is seated disc elements, generally indicated by the numeral 86. ed to receive a nut 81, a washer 88-and a backing plate Bil-lying beneath the nut and being confined thereby. The air metering disc is prefer ably circular and has a pair of openings orports 9|. A flat thermostatic spring element 9-2.1ies beneath the backing plate-89and normallycloses' the ports 9I. However, under certain conditions of operation, the thermostatic spring element- 92;:when heated may. curl upwardly to uncover. thexports 9|. 1

The. valve housing I9 at its lower end, has an L enlarged part 93 of the bore 83 and above thisisaformed a cylindrical portion 94. of. reduced diameter which constitutes a part of the metering section of the valve. Above the metering; sectionis-an enlarged portion 96 which connects with radial passages 91 which open into-re cesses 98 communicating with fuel nozzles. 99 and IN. The valve stem has a cylindrical part. I02 normally substantially in registry with the enlarged bore 93. Above the cylindrical part I02 isa tapered or other accurately formed section I03 which, when the valve i1, 18- is in'a partially open position, registers with the'cylindrical metering section 94.

Above the metering section of the valve stemis a part lllflof reduced diameter and above the reduced part I94 is a cylindrical section lllliwhich' forms the abutment which is engaged by the end ofthe-disc stem 85". The disc'stem ih'asja shoulder I'DTadapted to' engage a shoulder I98 formed" The upper end of the stem is 'threadin the bo're83 to limit the upward'movement ofthe air metering disc. A- spring 19- is seatedin the-bottom-of the passage 43 and engages the .bottom of the-valvestem, asshown at H0, to

5 urgethe valve-stem-andthe-disc stem an up-- ward-direction to close the fuelvalveand the air metering disc.-

floa-ting-sothatthevalve element 11 will accurately engageits seat I8.

At the upper end of the valve housing 19,- a

spring I I3'is coiled around the circumference of the' valve housing, asshown, and its end I I4 encircles and presses on the disc stem. This pressure exerted on the stem dampens thevibra- I tionof the parts.

Asshown in the drawings, evenwhen the valve 2 element "is on-its seat '18, a clearance existsat the metering gap between the metering section 94-of the valve housing and the taperedmeter ing-section I93 of the valve stem. However, as-

soon'as the valve element ll moves off its seat, the flow of fuel to theengine nozzles comes under the control of the fuel metering elements 94,- I 93; Downward movement ofthe valve stem increases the clearance between the parts and additional fuel is supplied to the nozzles, assuming constant times, a reservoir of fuel is maintained. When th'eengine is'operating and the valve", 78 is partially open the well of fuel is under pressure.

This arrangement insures a steady and uniform tween'the metering parts 94, I03. Moreover, since there is at all times a clearance atthe metering metering valve is opened slowly the displacement of fuel in the well .by the valve has almost.

no-effect insofar as increasing the. fuel flow through the meteringsection of the valve. How.- ever, if theengine is beingaccelerated rapidly,

thedisplacement-of the liquid in the well causes momentarily a somewhat increased fuel flow fio through the metering section of the valve.

Of particular importance is the factthat the wall of the air flow passage (Figure 1) from the pointrl l6 which marks the closed position of. the;

air:. metering disc, slopes outwardly and downwardly as shown at I H. The outward and downward slopinggshape of the Wall is accurately determined so that for any part-open position of the air-metering disc and the fuel metering valve,

the' proper ratio of fuel to air will be supplied inaccordance. with thespeed and load at which the engine is operaing. In general, the air flow pas-- sage is shaped so that the fuel to air ratio is. decreased with increased air flow and heavier loads preferably until approximately full throttle position is reached.

In the operation of the carburetor thus far described, fuel'is supplied to the fuel line 22 fromthe pump at substantially constant pressure.

This pressure with the particular fuel pump em- This constant pressure may be any desired amount and ployed is approximately five pounds.

is dictated by the particular pump with which mostautomotive engines are equipped. The resistance to flow caused by the fuel passages, betwee'n the fuel pump and the space below the Since movement of the air-- meter-ing disc is transmitted to the fuelmetering valve element H by theabutting relation of the stems, the fuel'v-alve stem issubstantiallyfree fuel pressure; The enlarged bore 93 acts as a well beneath the metering section in which, at all.

flow'of fuel throughout the annular space bediaphragm, drops the fuel pressure in the particular design shown, above the valve 3'1, 46, to about three pounds. It is the function of the diaphragm and pressure regulating spring 68 to maintain this pressure substantially constant so as to maintain a substantially constant pressure of fuel at the valve ll, 18. An increase in the pressure in the bore 38 and hence in the space below the diaphragm, exerts pressure on the diaphragm against the action of the spring 68, to cause the valve element 46 to move to a more closed position. In such adjusted position, the resistance to fuel fiow is increased thus decreasing the pressure in the fuel supply line 22 or maintaining the pressure at the valve l1, 18 constant,

The above action will occur if the pump is not delivering fuel at constant pressure. However, the more important cause of fluctuating pressure results from demand for fuel caused by fluctuations in the position of the air metering disc. When the engine demands more fuel due to greater air flow, the fuel metering valve opens more widely and causes a drop in the fuel pressure at the fuel metering valve. However, this drop in pressure immediately results in a lessening in pressure on the underside of the diaphragm. This action opens the valve 31, 46 more widely to decrease the resistance to fuel flow through the valve 31, 46 to permit a larger portion of the pressure of the pump to be available at the fuel metering valve. It will thus be appreciated that the diaphragm is constantly correcting for fiuctuations in fuel demand to maintain the fuel pressure at the metering valve substantially constant to insure accurate metering. In this manner the fuel pressure is maintained substantially constant under average or cruising conditions of operation of the engine.

Under certain conditions of operation it is desirable to increase the fuel-air ratio. Such a condition occurs, for example, when the engine is under heavy or substantially full load, as when the engine is going up a hill, when the engine is being rapidly accelerated or driven at substantially full speed. As previously mentioned, the position of the parts shown in the drawings is that when the engine is at rest. As soon as the engine is running the piston 58 moves upward to engage the stop 66. It is maintained in this position as long as the partial vacuum in the intake manifold is at a high value. However, should the engine become heavily loaded, or should the engine be rapidly accelerated, a pressure increase (decrease in the partial vacuum) in the intake manifold occurs, resulting in an increase in pressure in the cylinder 51 above the piston.

This increased pressure, assuming it is large enough, results in the spring 69 urging the piston in a downward direction toward engagement with the head of the nut 48 increasing the pressure on spring 68. I have found in practice, that it is desirable that this action occur when the sub-atmospheric pressure in the cylinder 5'! is such that it approximates full load on the engine or approximately full throttle position. However, the sub-atmospheric pressure conditions at which this action should occur is a matter of choice and may be made any desired amount within reasonable limits. In general, it may be made to occur at any point in the curve formed by plotting the fuel-air ratio against the air flow.

The piston is ineffective to exert any influence on the diaphragm until the pressure in the cylinder 5! above the piston is greater than the set value. However, as soon as the piston moves off its seat 66, it immediately exerts an influence on the diaphragm either through the spring 68 or directly upon engaging the head 48 of the nut. In any event, the diaphragm is moved downward so as to increase the opening through the valve 31, 46; decrease the resistance to fuel flow therethrough; and increase the fuel pressure available in the fuel passage 22 and at the valve 71, 18. This increase in fuel pressure for any particular position of the air metering disc and the fuel metering valve, increases the fuel fiow through the fuel metering valve and hence, the discharge of fuel through the nozzles 99 and I01. Thus the fuel-air ratio is increased automatically at or near full load for any particular engine speed or when the engine is suddenly accelerated.

As soon as the engine operating conditions return to normal, as when the load on the engine is decreased or the acceleration of the engine is terminated, the partial vacuum in the cylinder 51 increases again. The piston returns into engagement with the stop 66 and complete control of the diaphragm is taken over by the fuel pressure beneath the diaphragm and the spring 68. Thus the mechanism shown in Figure 3 is a combined pressure regulating valve and full load enrichment valve, the system functioning to maintain the fuel pressure continuously constant during normal conditions of operation and functioningto increase the presssure, and hence the fuel flow, under temporary engine load conditions. The full load enrichment device not only enriches the mixture when the engine is under heavy load, is rapidly accelerated or driven with substantially full throttle but also has a function during starting. At cranking speed, the engine does not develop sufficient vacuum to lift the piston into engagement with its stop. Consequently a rich mixture is being supplied to the engine for starting by this and additional means as will presently appear. Thus the additional charge of fuel for starting is atomized in the same manner as the regular fuel supply to the carburetor instead of being drawn into the carburetor in a large unvaporized stream as in the conventional carburetor.

As previously mentioned, Figure 1 is a diagrammatic view and the nozzles 99 and H, in this view, are shown out of their true position. Actually they are positioned at right angles to the position shown in Figure 1. The true position of the nozzles is shown in Figure 4 in which position the nozzles are in a plane parallel to the plane of the row of cylinders. While I have shown only two nozzles, it will be appreciated that any desired number of nozzles may be employed.

The nozzle 99 is provided with a bore, which is in communication with one of the recesses 98, while the nozzle IUI is provided with a bore which is in communication with the other recess 98. The nozzles are designed to provide unequal flow resistance. This may be accomplished either by making the bores of unequal diameter, or by having the nozzles of unequal length as shown in the drawings. The purpose of this arrangement is to cause the flow of the fuel to take place through the nozzle 99 at low air flows and have the nozzle Hll function primarily at relatively high air flows.

It will be appreciated that the greater length of the nozzle [III will cause the fuel to discharge through the short nozzle 99 when the volume of wags-wave a :fuel being .supplied:is.-withln thercapacityzof'zthe inozzle 99. *"sWhen :theevolume :of "fuel'flow increases, .the resistance to flow tthrough'ithe nozzle f 99 increases and :at.a:certain:point,r-the-resistance to=flow through ithe nozzle 43 9 :becomes sufiicient to enablea portion ofithe' fuel to bedischarged through the nozzle I10 1 ,partial -vacuum .exists in. -the flow passage under all normal conditions:of-operation. Thus there is .a,relative,ly-;large pressure difference between the pressure of the fuel and the pressure of the air. This increased pressure difference assists in securing-better-atomizationofathefuel and more uniform distribution of the fuel through the air streamflowing through-the air passage. Of particular importance in securing better atomization of thefuel is that the plane of the-air metering disc is normal -to -the-'direction--of air flow. This-arrangement results in extremely turbulent air conditions in the -air flow passage assisting in breaking up thefuel as it is discharged under pressure into-the' air'stream.

While I have shown the preferred formof the carburetorof my invention it -will be apparent that :various changes and modifications maybe made therein, particularlyin the form-andrela- :tion of parts, without departing from the spirit of my invention as set :forth in the appended claims. i

I claim:

1. In an internal combustion carburetor having a fuel line through which fuel is pumped at substantially constant pressure and wherein the engine has an intake manifold comprising, in combination, pressure regulating means in said line, means for controlling the resistance to fuel flow of said pressure regulating means to maintain the fuel pressure on the discharge side of said pressure regulating means substantially constant under the normal range of conditions of engine operating load, and means subject to intake manifold pressure for decreasing the resistance to flow of said pressure regulating means to increase the fuel to air ratio only upon a predetermined increase in the load on the engine above the normal range.

2. In an internal combustion carburetor having a fuel line through which fuel is pumped at substantially constant pressure and wherein the engine has an intake manifold comprising, in combinatign, a valve in said line, means for controlling the position of said valve to maintain the fuel pressure on the discharge side of said valve substantially constant under the normal range of intake manifold pressure, and means movable at least partly by intake manifold pressure only when said pressure is above the normal range for increasing the fuel pressure on the discharge side of said valve.

3. An internal combustion engine carburetor having an air passage connected to the intake manifold comprising, in combination, a member in said air passage movable from a position substantially to close said passage to an open position in accordance'with the pressure conditions existent in said air passage, a fuel line through which fuel is discharged under pressure into said air passage, a fuel metering valve in said fuel line operatively connected to said member, means including a pressure regulating valve in said line for maintaining the pressure of fuel at the metering valve substantially constant under the normal .range of engine load conditions, and means subject to engine manifold pressure for opening said pressure regulating valve toa greater extent to increase the fuel pressure at the metering valve upon the engine being subjected to predetermined iincreased load conditions above the normal range.

4. An internal combustion engine carburetor having an air passage connected to the intake manifold comprising, in combination, a member wiin said air passagemovable from a position substantially to closesaidpassage to an open position'in accordance with the pressure conditions existent insaid air passage, a fuel line through which fuelis discharged under pressure into said .airzpassage, a fuelmeteringvalve in said fuel line operatively connected to said member, a substantially constant-, pressure fuel pump, means including a pressure regulating valve in sai'd'line between the fuel pump and themetering valve for maintaining the pressure of fuel at themetering ..valve substantially constant under normal load conditions, and means including pressure responsive means acting on said pressure regulating valve forincreasing the fuel pressure at the metering valve upon the engine being subjected .to predetermined increased load conditions.

5. Aninternal combustion engine carburetor having-an air-passage connected to the intake manifold comprising, in combination, a member in said air-passage movable from a positionsubstantiallytoclose said passage to an open posi- :-tion in accordance swith thezpressure conditions existent in said air passage, a fuel line through which fuel is discharged under pressure into said air passage, a fuel metering valve in said fuel line operatively connected to said member, a pressure regulating valve in said line, means including a pressure responsive element for controlling the regulating valve so as to maintain a substantially constant pressure. of fuel at the metering valve under the normal range of conditions of operation of the engine, and means including a second pressure responsive element subject to intake manifold pressure for modifying the controlling action of said first pressure responsive element to increase the fuel to air ratio when the engine is subjected to predetermined increased load conditions above the normal range.

6. In an internal combustion engine carburetor having an air passage connected to the intake manifold and a throttle located in the air passage, in combination, a member in said air passage movable from a position substantially to close said passage to an open position in accordance with the pressure conditions in said air passage, a fuel metering valve, means connecting said fuel metering valve and member so that the amount of movement of the fuel meterin valve is substantially proportional to the amount of movement of said member, a fuel line connected to a source of fuel under pressure through which fuel is discharged under the metering action of said fuel metering valve into said passage, means between the source of fuel and the fuel metering valve for maintaining the pressure of fuel at said fuel metering valve substantially constant during normal running conditions of the engine comprising a pressure regulating valve in said fuel line, a pressure responsive element connected to said pressure regulating valve, said pressure responsive element on one of its sides being subject to the pressure of fluid on the discharge side of said pressure regulating valve, a spring on the other side of said pressure responsive element urging said pressure regulating valve toward a more open position, means for modifying the action of said pressure responsive element comprising a pressure responsive member engaged on one side by said spring, a second spring on the other side of said pressure responsive member, and means for subjecting said other side of the pressure responsive member to the fluctuations in intake manifold pressure.

7. An internal combustion engine carburetor having an air passage connected to the intake manifold comprising, in combination, means for metering the air flowing through said passage, a fuel metering valve, means responsive to the air metering means for actuating the fuel metering valve, a fuel line through which fuel is fed at substantially constant pressure, means including a pressure responsive element for normally maintaining a constant fuel pressure at the fuel metering valve regardless of the volume of fuel flowing through said fuel metering valve, means subject to intake manifold pressure for increasing the pressure of fuel at said fuel metering valve and the flow of fuel therethrough, said last men-: 7 tioned means including a second pressure responsive element, a spring urging said second pressure responsive element into engagement with said first pressure responsive element, means in- V cluding a connection to the intake manifold for subjecting the said second pressure responsive element to intake manifold pressure and within the normal range of fluctuations in intake manifold pressure to retain said second pressure responsiv'e element ineffective to exert any influence on said first pressure responsive element, said second pressure responsive element being movable into effective engagement with said first pressure responsive element under the influence of said spring to increase the pressure on said first pressure responsive element upon a predetermined increase in intake manifold pressure above the normal range.

FRANK B. SWEENEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,191,488 Watts July 18, 1916 1,787,230 Atkins Dec. 30, 1930 1,826,630 Moore Oct. 6, 1931 1,933,365 Chandler et a1. Oct. 31, 1933 1,942,004 Schramm Jan. 2, 1934 1,955,037 Viel Apr. 17, 1934 1,982,049 Fageol Nov. 27, 1934 2,128,079 Dawes Aug. 23, 1938 2,166,899 Blattner July 18, 1939 2,216,422 Schimanek Oct. 1, 1940 2,262,408 Read Nov. 11, 1941 2,318,216 Garretson May 4, 1943 2,392,055 Mennesson Jan. 1, 1946 2,445,099 Wirth July 13, 1948 2,447,264 Beardsley Aug. 17, 1948 2,448,131 Williams et a1 Aug. 31, 1948 2,499,554 Wirth Mar. 7, 1950 

